Ludum Dare is a regularly-held event to challenge people to create a videogame in 48 hours. The LD23 interactive keynote is here.
The event has grown quite large, with over 1400 games created last weekend. Some are good, some are bad, but in some cases it's people creating their first game, and I think that's cool. I'd known about it for a while, but figured since last week was the 10th anniversary, and I had some time, I'd try to make one. My entry is "boing SMASH", and it's here. Anyway, you can click "View All" from that page to see lots more games to try.